1. Field of the Invention
The invention relates to retractors that are used in various types of surgeries such as cardiovascular surgery and, more particularly, to a retractor that permits such operations to be conducted with minimal trauma to the patient.
2. Description of the Prior Art
In the course of such operative procedures as mitral valve surgery and mammary artery surgery, it is necessary to expose the heart. Such exposure traditionally has been accomplished by performing a full sternotomy (cutting an incision completely through the sternum and retracting the sternum). The retraction is accomplished by a retractor that employs parallel grips that engage the edges of the separated sternum. The grips are mounted perpendicularly to a toothed crossbar. One of the grips is fixed to one end of the crossbar, while the other grip is movably mounted to the crossbar by means of a pinion that engages the teeth of the crossbar. Upon rotating the pinion, the movable grip can be moved away from the fixed grip, thereby retracting the sternum so as to expose the heart. A retractor of the type described is shown in U.S. Pat. No. Re. 34,150, issued Dec. 29, 1992 to A. E. Santilli and D. M. Cosgrove III (“the '150 patent”), the disclosure of which is incorporated herein by reference.
A surgical retractor that is less invasive than that disclosed in the '150 patent is disclosed in U.S. Pat. No. 6,099,468, issued Aug. 8, 2000 to A. N. Santilli and A. Patel (“the '468 patent”), the disclosure of which is incorporated herein by reference. The retractor according to the '468 patent includes a pair of very small parallel grips that are mounted to a toothed crossbar. As in the device disclosed in the '150 patent, the grips are disposed at the ends of arms that extend at right angles from the crossbar. One of the arms is fixed to one end of the crossbar, while the other arm is movable along the crossbar by means of a pinion so that the grips can be moved toward or away from each other.
The retractor according to the '468 patent is smaller than prior retractors, and therefore less invasive. By using the retractor according to the '468 patent, a partial sternotomy, rather than a full sternotomy, can be performed in order to have access to the heart. While the retractor according to the '468 patent is less invasive, it can retract the sternum or ribs only in one plane. That is, the sternum or ribs are pulled straight apart. There are a variety of circumstances in which it is desirable not only to retract the sternum or ribs, but also to lift one side of the incision relative to the other.
A surgical retractor that permits one side of the incision to be lifted relative to the other side is disclosed in U.S. Pat. No. 6,361,492, issued Mar. 26, 2002 to Albert N. Santilli (“the '492 patent”), the disclosure of which is incorporated herein by reference. As in the device disclosed in the '468 patent, the retractor disclosed in the '492 patent includes relatively small grips or paddles that are inserted through a small opening formed between adjacent ribs or a portion of the sternum. The retractor in question includes a two-part toothed crossbar that has a pivoted connection at or near its center. The retractor has a crank mechanism connected between the opposed arms that permits the arms to be pulled toward or away from each other in order to pivot the crossbar about the pivot. Such pivoting of the crossbar enables one arm to be lifted relative to the other. In turn, one side of the incision can be lifted relative to the other side.
While the device according to the '492 patent is effective to lift one side of the incision, there are many situations in which there is no need, or it is undesired, for the retractor to have pivoting portions. It would be desirable to be able to lift one side of the incision relative to the other without the complexity, expense, or bulkiness of a pivot and accompanying crank mechanism. Any such retractor preferably would permit minimally invasive surgical procedures to be performed.